Measurement method and encoder device, and exposure method and device

Abstract

There is provided an encoder device to measure a relative moving amount between a first and second members. The encoder device includes: a reflective-type diffraction grating on the first member; a light source unit to radiate a measuring light; a first optical member on the second member; a first and second reflecting units on the second member that cause first and third diffracted lights generated via diffraction of the measuring light and having orders different from each other to come into the diffraction grating respectively, and cause second and fourth diffracted lights generated via diffraction of the first and third diffracted lights respectively to come into the first optical member; photo-detectors configured to detect interference lights between two diffracted lights and other light beam respectively; and a measuring unit to obtain the relative moving amount by using detection signals from the photo-detectors.

What is claimed: 
     
       1. An encoder device configured to measure a relative moving amount between a first member and a second member, the second member being supported to be movable relative to the first member at least in a first direction, the encoder device comprising:
 a reflective-type diffraction grating provided on the first member and having a grating pattern of which periodic direction is at least the first direction; 
 a light source unit configured to radiate a measuring light; 
 a first optical member provided on the second member and causing the measuring light to come into a first position on a surface of the grating pattern of the diffraction grating; 
 a first reflecting unit provided on the second member and causing a first diffracted light, which is generated, via diffraction of the measuring light, from the diffraction grating in the first direction, to come into a second position on the diffraction grating; and 
 a second reflecting unit provided on the second member and causing a second diffracted light, of which order is different from an order of the first diffracted light and which is generated, via diffraction of the measuring light, from the diffraction grating in the first direction, to come into a third position on the diffraction grating, 
 wherein both of the second position and the third position are different, in a second direction perpendicular to the first direction, from a first line segment at which a first plane and the reflective-type diffraction grating cross or intersect, the first plane including the first position, a path of the first diffracted light travelling from the diffraction grating to the first reflecting unit and a path of the second diffracted light travelling from the diffraction grating to the second reflecting unit. 
 
     
     
       2. The encoder device according to  claim 1 , wherein
 a second line segment, which passes through the first position in the second direction, is positioned on the reflective-type diffraction grating between the second position and the third position. 
 
     
     
       3. The encoder device according to  claim 1 , wherein
 a third line segment passing through the second position and the third position is parallel to the first line segment. 
 
     
     
       4. The encoder device according to  claim 1 , wherein
 the first reflecting unit transfers the first diffracted light in the second direction, and 
 the second reflecting unit transfers the second diffracted light in the second direction. 
 
     
     
       5. The encoder device according to  claim 1 , wherein
 the first reflecting unit causes a third diffracted light, which is generated, via diffraction of the first diffracted light, from the diffraction grating, to come into the first optical member, and 
 the second reflecting unit causes a fourth diffracted light, which is generated, via diffraction of the second diffracted light, from the diffraction grating, to come into the first optical member. 
 
     
     
       6. The encoder device according to  claim 5 , further comprising:
 a first photo-detector configured to detect an interference light generated by interference between the third diffracted light via the first optical member and other light flux than the third diffracted light; 
 a second photo-detector configured to detect an interference light generated by interference between the fourth diffracted light via the first optical member and other light flux than the fourth diffracted light; and 
 a measuring unit configured to obtain the relative moving amount between the first member and the second member by using detection signals from the first and second photo-detectors. 
 
     
     
       7. The encoder device according to  claim 1 , wherein
 the second position and the third position are located on a same side, in the second direction, relative to the first line segment. 
 
     
     
       8. An exposure apparatus configured to expose an object to be exposed with a pattern, the exposure apparatus comprising:
 a frame; 
 a stage configured to support the object and configured to be movable relative to the frame at least in a first direction; and 
 the encoder device as defined in  claim 1  configured to measure a relative moving amount between the frame and the stage at least in the first direction. 
 
     
     
       9. A method for measuring a relative moving amount between a first member and a second member, the second member being supported to be movable relative to the first member at least in a first direction, the method comprising:
 causing a measuring light to come into a first position on a grating pattern, of which periodic direction is at least the first direction, of a reflective-type diffraction grating provided on the first member; 
 causing a first diffracted light, which is generated, via diffraction of the measuring light, from the diffraction grating in the first direction, to come into a second position on the diffraction grating; and 
 causing a second diffracted light, of which order is different from an order of the first diffracted light and which is generated, via diffraction of the measuring light, from the diffraction grating in the first direction, to come into a third position on the diffraction grating, 
 wherein both of the second position and the third position are different, in a second direction perpendicular to the first direction, from a first line segment at which a first plane and the reflective-type diffraction grating cross or intersect, the first plane including the first position, a path of the first diffracted light travelling from the diffraction grating to the first reflecting unit and a path of the second diffracted light travelling from the diffraction grating to the second reflecting unit. 
 
     
     
       10. The measuring method according to  claim 9 , wherein
 a second line segment, which passes through the first position in the second direction, is positioned on the reflective-type diffraction grating between the second position and the third position. 
 
     
     
       11. The measuring method according to  claim 9 , wherein
 a third line segment passing through the second position and the third position is parallel to the first line segment. 
 
     
     
       12. The measuring method according to  claim 9 , wherein
 causing the first diffracted light to come into the second position includes causing the first diffracted light to be transferred in the second direction, and 
 causing the second diffracted light to come into the third position includes causing the second diffracted light to be transferred in the second direction. 
 
     
     
       13. The measuring method according to  claim 9 , wherein
 the second position and the third position are located on a same side, in the second direction, relative to the first line segment. 
 
     
     
       14. An exposure method for exposing an object to be exposed with a pattern, the object being supported by a stage configured to be movable relative to a frame at least in a first direction, the exposure method comprising measuring a relative moving amount between the stage and the frame at least in the first direction by using the measuring method as defined in  claim 9 . 
     
     
       15. A method for producing a device, comprising a lithography step, wherein an object is exposed in the lithography step by using the exposure apparatus as defined in  claim 8 . 
     
     
       16. A method for producing a device, comprising a lithography step, wherein an object is exposed in the lithography step by using the exposure method as defined in  claim 14 . 
     
     
       17. An encoder device for measuring a relative moving amount between a first member having a diffraction grating and a second member, a positional relation between the first and second members being changeable at least in a first direction, the encoder device comprising:
 a light splitter which splits a light from a light source so as to generate a measuring light to come into the diffraction grating and a reference light; 
 a first optical member which causes a first diffracted light to come into the diffraction grating, the first diffracted light being generated at the diffraction grating via diffraction of the measuring light coming into the diffraction grating; 
 a second optical member which causes a second diffracted light to come into the diffraction grating, the second diffracted light being generated at the diffraction grating via diffraction of the measuring light coming into the diffraction grating; 
 a first photo-detector which photo-electrically detects a first interference light generated by interference between a third diffracted light and the reference light, the third diffracted light being generated at the diffraction grating via diffraction of the first diffracted light coming into the diffraction grating; 
 a second photo-detector which photo-electrically detects a second interference light generated by interference between a fourth diffracted light and the reference light, the fourth diffracted light being generated at the diffraction grating via diffraction of the second diffracted light coming into the diffraction grating; and 
 a calculator which calculates the relative moving amount between the first and second members in the first direction by using a first output from the first photo-detector and a second output from the second photo-detector, 
 wherein, in the first direction, a second position at which the first diffracted light comes into the diffraction grating and a third position at which the second diffracted light comes into the diffraction grating are different from a first position at which the measuring light comes into the diffraction grating; 
 wherein the second position and the third position are different, in a second direction crossing the first direction, from the first position; 
 wherein the second position and the third position are located on a same side, in the second direction, relative to the first position. 
 
     
     
       18. The encoder device according to  claim 17 , wherein
 the calculator calculates a relative moving amount between the first and second members in the first direction and a relative moving amount between the first and second members in a third direction crossing a surface of the diffraction grating. 
 
     
     
       19. The encoder device according to  claim 17 , wherein
 the first optical member changes a travelling direction of the first diffracted light travelling to the diffraction grating such that the travelling direction is parallel to a travelling direction of the measuring light travelling to the diffraction grating. 
 
     
     
       20. The encoder device according to  claim 17 , wherein
 a travelling direction of the measuring light travelling to the diffraction grating is perpendicular to a surface of the diffraction grating. 
 
     
     
       21. The encoder device according to  claim 17  wherein
 the light splitter reflects one portion of the light from the light source so as to generate the measuring light and transmits another portion of the light from the light source through the light splitter so as to generate the reference light, or the light splitter transmits one portion of the light from the light source through the light splitter so as to generate the measuring light and reflects another portion of the light from the light source so as to generate the reference light. 
 
     
     
       22. An exposure apparatus which expose a pattern onto an object to be exposed, the exposure apparatus comprising:
 a frame; 
 a stage which supports the object to be exposed and which is capable of moving relative to the frame at least in a first direction; and 
 the encoder device as defined in  claim 17  configured to measure a relative moving amount between the frame and the stage at least in the first direction.